How much can you learn about your health from a dab of poop or a swab from your skin or mouth? With various scientific researchers offering to test your microbiome for a fee, it's natural to be curious about the trillions of microbes living in your body. But is it worthwhile to get tested yourself, and what can current tests really tell you about your own health?

The Human Microbiome Project is an incredibly exciting collection of research, one that may someday yield highly personalized medical treatments and teach us about the impact of various microbial ecosystems on specific aspects of human health. Currently, there are research organizations that offer microbial testing kits, such as uBiome and the American Gut Project. You buy a kit, send in your sample (your gut bacteria can be tested, but so can the bacteria from other parts of your body, including your mouth and skin), receive your microbiome data, and then compare yourself to other people who have had their microbiomes tested.

It's a neat idea, and with research exploring the relationship between the microbiome and everything from intestinal disorders to mental health, a very enticing one. What if understanding the makeup of the various microbes in our bodies could help diagnose ailments we didn't even know we had? What if it could predict diseases we're at risk of developing down the line?

In a lot of ways, these tests resemble those home genetic testing kits, where you send in a swab and receive information about your personal genetic makeup. But those tests have not been without controversy. Just this past December, genetic testing company 23andMe agreed to comply with FDA demands that the company stop making health claims related to customer's genetic data. That means that, while customers can still receive their raw genetic data from 23andMe, the company can no longer claim that you may be predisposed to a particular disease or have a specific response to a particular drug. There is still a gap between identifying specific genes and understanding how to apply them to our health.

So what about microbiome testing? What can it tell us about what's going on inside our bodies? And what, if anything, can it tell us about our health now or in the future?

Why You Can't Take Your Microbiome Test to Your Doctor

While researchers have already made great strides in examining the human microbiome, researchers note that we are still just five or six years into studying the microbiome. "We are gathering incredibly detailed, rich data about the microbiome," says Lita Proctor, Program Director of the National Institute of Health's Human Microbiome Project, "but the reason, I presume, that most people want to have their microbiome tested is that they want to learn whether they're considered healthy, whether they have some impending disease or condition that's on the horizon or if they can do anything to modify their microbiome, increase its robustness and so on. You're motivated to want to improve your health or to cure some condition or disease that you may have. And that's tricky. It's tricky for a lot of reasons."

"We're not sure what 'composition' means in the makeup of the microbiome," she notes. For example, some research groups believe that humans have different microbiome "types," similar to blood types, called enterotypes. However, other groups, including the HMP, have not been able to replicate those enterotypes. "On the other hand," she concedes, "I think the HMP acknowledges that this is still very early days. As we gather more data, we might start to see people fall out into different groups tied to their environment, to their diet, and genetics, and so on."

Joseph Petrosino, Director of the Alkek Center for Metagenomics and Microbiome Research at the Baylor College of Medicine, adds that while some studies have found correlations between certain microbial signatures and conditions like obesity, type 2 diabetes, and irritable bowel disease, it is too early to know whether those microbial signatures are part of the cause or part of the effect of those conditions. He does note that, when looking at the data from their own microbiome tests, individuals might look for a diverse microbiome or high levels of microbial generalities associated with health. But even then, he cautions, it's difficult to say that a certain microbiome makeup identifies a person as healthy. He explains, "In the Human Microbiome Project, they found in a very small cohort of individuals that even the taxa that people thought to be associated with health, the Bacteroides genus, you could be at a status of health that we call 'no overt signs of disease,' you could have five percent of your microbiome comprised of this taxa or you could have 95 percent, or anywhere in between. So it was very hard to associate a taxa with being particularly healthy."

There is also the problem of the breadth of the human microbiome studies so far. Proctor points out that, while some countries are working on national-scale human microbe studies, most microbe studies thus far have been performed primarily on white Westerners, which limits our understanding of how environment and genetics interact with the microbiome. Also, your microbiome isn't a static ecosystem; it changes throughout your life in ways we are still investigating.

It's natural for people to want to see what's going with their microbes and to want to find ways to control their own health. "I've had my microbiome sequenced," says Petrosino. "It's interesting to know what's inside of you. And you wonder, 'Hey, is that probiotic I'm taking showing up anywhere?'" But if you're interested in the test for the sole purpose of manipulating your microbiome or predicting your future, you may want to wait. "For the 'worried well' looking at their microbiome data and thinking, 'I'm hosed," or "I'm looking pretty good," it's a little bit premature for that," Petrosino says.

Don't DIY Your Microbiome

Researchers studying the human microbiome are excited by the public interest in the microbiome, but in some cases a little bit of knowledge misapplied can be a dangerous thing. Proctor points to a curious case regarding fecal transplants. In some instances, people with debilitating gut diseases, such as ulcerative colitis, have received enema infusions of stool from healthy donors and apparently recovered from their illness. However, Proctor adds, "We have no idea what the microbiological or biochemical properties that are contributing to that recovery from ulcerative colitis."

Some lay people have taken this idea of fecal transplants and run with it, performing their own fecal transplants at home. That's right, folks are finding donors to provide them with stool, making stool smoothies, and then giving themselves stool enemas without medical supervision. (Proctor notes that this is a bit bizarre for a culture where people smear hand sanitizer over the handles of their shopping carts.) And they are doing this in attempt to "treat" conditions that there is no scientific evidence can be treated with fecal transplants, such as obesity. Plus, they may be unknowingly exposing themselves to harmful pathogens. Proctor says, "We're seeing the application of knowledge about the microbiome being applied so rapidly and without careful study that I, as a scientist, have a fear that some people may go, 'Oh yeah, we know enough about the microbiome to be able to conduct these kinds of activities.' I'm fearful that there could be some unintended consequences."

She also cautions that people should not be looking to the human microbiome as the be-all end-all of human health. We should be thinking of the microbiome as another organ, she says, another thing to look for in human health. She also notes that it's not a good idea to think of the microbiome as somehow separate from the rest of the human body. When you treat the microbiome, you're treating the rest of the body as well.

Why You Should Consider Getting Tested Anyway

So you can't use your microbiome to predict health or recommend medical treatments at this point. Does that mean you shouldn't get yours tested? Assuming you're not going to run off and give yourself a stool enema, there are actually some very good reasons to have your microbiome tested if you have the money to spend on it.

For one thing, these tests can really tell you what microbes are inside of you, even if they can't tell you exactly what that means. "That's just human curiosity," notes Proctor. "That's worth doing."

More significantly, though, having your microbiome tested by one of these companies is a way to participate in and fund research into the microbiome. Proctor points out that these testing companies are operated by trained scientists who are analyzing the data and publishing peer-reviewed papers based on their findings. These papers, she notes, have the same currency as research funded in any other way, and the true test of the research is in the peer-review process.

Petrosino agrees, adding that there is value in an individual contributing their data to a much larger study, "What is going on is that you're contributing your sample to a much larger cohort of individuals who then can be studied as a whole. And perhaps your sample, if you happen to have a condition, be it celiac disease or whatnot, will lead to a better understanding of the full breadth of the impact of that condition on the microbiome."

Even if you can't derive any clinical meaning from your individual test in the short term, sending your sample to one of these companies is a way to participate in a larger scientific research project, one that could have an enormous impact on our understanding of the human body. "There's probably limited information you can get by yourself for a study like this," says Petrosino, "but in the end, you're contributing to science—and perhaps to [the understanding of] a condition that you may or may not have."